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https://designers-guide.org/forum/YaBB.pl Simulators >> AMS Simulators >> Floating node using spectre option https://designers-guide.org/forum/YaBB.pl?num=1532953895 Message started by Gp on Jul 30th, 2018, 5:31am |
Title: Floating node using spectre option Post by Gp on Jul 30th, 2018, 5:31am Hello All, How can I found floating node in design using spectre option? Another question is, any difference between the floating and dangling node? Thanks. |
Title: Re: Floating node using spectre option Post by Geoffrey_Coram on Aug 1st, 2018, 7:14am A dangling node usually means there's only one connection (but it's a resistive path). If you had r1 dangle 0 50 then "dangle" is dangling, but not floating. If you had c1 dangle 0 1p or if you have c1 float 0 1p c2 float 0 2p then these nodes are both floating -- no dc path to ground. But "float" has two connections, so it's not considered dangling. |
Title: Re: Floating node using spectre option Post by Horror Vacui on Jul 24th, 2019, 5:32am Is there any spectre option which could REPORT any potential floating and/or dangle instances? It could be a useful way to narrow down the cause of convergence issues. |
Title: Re: Floating node using spectre option Post by Ken Kundert on Jul 24th, 2019, 11:46am The topology checker naturally finds, reports, and fixes nodes without a DC path to ground, which includes floating nodes. Dangling nodes do not cause convergence issues as long as they have a DC path to ground. Dynamic floating nodes (generally caused by Verilog-A models) are not reported with a dedicated message. Instead, the simulation fails with a 'Singular Jacobian'. When it does, it generally reports the nodes or branches where the problem was found. This often leads you to the problematic node or branch. -Ken |
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